A. Field of Invention
This invention pertains to a device which can be installed in a motor vehicle such as an automobile, a truck or a sports utility vehicle. More particularly, the subject invention pertains to a device which automatically disconnects the battery of motor vehicle and selectively reconnects the same on demand.
B. Description of the Prior Art
A critical part of any automotive vehicle is its battery which provides power for various primary and secondary systems. Normally an automotive battery can last for a relatively long time since its charge is refreshed continuously as the vehicle is operated. However, in some instances, such as for example, when a short occurs in the vehicle wiring, or a control switch malfunctions, a leakage current may flow even when the engine is off, discharging the battery.
In order to protect the battery from such an occurrence, several proposals have been made for devices that can interrupt undeniable leakage current flow. However, the devices proposed so far have disadvantageous features which makes them undesirable. One such feature is that they interpose a relatively high series resistance between the battery and the car wiring. Therefore a high IR drop is developed, especially at high current drains, thereby reducing the voltage that is available to the vehicle systems, wasting energy, and generating undesirable heat.
A further disadvantage of the proposed devices is that they may not stand up to the extremely hostile environment existing under the hood of motor vehicles. This environment is characterized by high temperatures as well as corrosive fumes which damage sensitive electronic circuitry.
In view of the above, it is an objective of the present invention to provide a battery disconnect device with a very low in line resistivity.
A further objective is to provide a device in which the moving parts are sealed in a water and air tight chamber so that they are protected from noxious fumes and other undesirable fluids.
Other objectives and advantages of the invention shall become apparent from the following description.
Briefly, a battery disconnect device for an automotive vehicle includes a sense/trip circuit that sense a preselected condition of a motor vehicle battery; connecting elements such as bars connecting said battery to the vehicular equipment; and a solenoid having a coil and a contactor disposed within a closed chamber and associated with said coil. The coil is activated when an abnormal condition is sensed. The contactor has a first position in which said contactor connects said connecting elements, a second position in which said contactor is removed from said connecting elements. A biasing spring is arranged to urge said contactor toward said first position to generate a force between said contactor and said connecting elements to reduce the in-line device resistivity. A magnet is also provided within the solenoid to keep the contactor in the second position, once the coil has been activated, said second position thereby being maintained even after the coil has been deactivated. A manual push button is used to move the contactor away from the first position until it snaps back to the first position.
Additional elements are used to provide other advantageous features. One such element is a remote trip circuit which allows the solenoid to be tripped remotely thereby allowing the device to be used as an antitheft device. In addition to the pushbutton, a remote close circuit may also be used to close the solenoid. The remote close circuit and/or the remote trip circuit could be activated by a portable transmitter.
The device may further include an indicator for showing when the battery is overcharged, as well as a shunt circuit to allow a trickle current to flow between the battery and the motor vehicle bus for powering certain equipment in the car.